1. Field of the Invention
The present invention relates to fixed and movable turbine blades, intended in particular for use in a turbojet engine, comprising at least one internal cavity which, in use, is swept by cooling air, and an outer wall defining a leading edge zone, an intrados face and an extrados face of the blade, the wall including rows of holes communicating with the internal cavities for the escape of cooling air.
2. Summary of the Prior Art
Blades of this type are well known, and an example is disclosed in EP-A-0562944 in which at least one row of holes communicating with a first longitudinal internal cavity of the blade is disposed in the leading edge zone of the blade on opposite sides of the center line of the leading edge, the holes being distributed over the height of the blade and arranged in an angular pattern, and each hole having an oblong section and being inclined so that its inner end is closer to the root of the blade than its outer end. In a preferred embodiment, there are two of these rows forming a first double row, and two second rows of holes, also communicating with the first cavity, arranged on opposite sides of the leading edge of the blade, one beyond each of the first rows.
In spite of such improvements, the continual increase in the temperature at the inlet of turbomachine turbines, and particularly in aircraft engines, makes it necessary to continue to seek optimum cooling of the constituent parts of the turbine with the additional aim of extending the life of the parts and optimizing the performance. The leading edge of turbine blades, whether in fixed guides or bladed turbine wheels, constitutes a particularly critical area as it is directly exposed to the whole of the gases at their highest temperature, and the creation of a film of cold cooling air at this position is hardly possible.
Accordingly, it is an object of the invention to improve the cooling of a turbine blade of the type described above, while retaining its other known characteristics necessary to ensure the required operating conditions.